It is generally known in many industrial operations to coat surfaces of containers, tools or other surfaces with a release agent to prevent material which comes into contact with such surfaces from adhering thereto. For example, Couleau et al. (U.S. Pat. No. 4,609,570) disclose that it is generally known in the art of molding concrete pieces, to coat mold surfaces which come into contact with the material being molded with a product which facilitates the unmolding and which attains a satisfactory surface condition for the pieces. Known release compositions generally constitute a mixture of organic solvents and petroleum products to which are added active release ingredients. Couleau et al. propose a non-petroleum based release agent for use in concrete applications, which is an aqueous antifreeze solution including a combination of at least one active release constituent which may be an organic acid salt, at least one clarifying anti-freeze agent which may be a hydroxyethylether, at least one spreading agent which is an ester, and at least one polyether lubricating agent.
Ballenger, Jr. et al. (U.S. Pat. No. 5,186,979) also disclose that in the transporting and handling of hot-mix asphalt, it is necessary to treat the dump truck or trailer with a suitable release agent to prevent the asphalt mix from sticking to the walls thereof. It is disclosed that petroleum oils have been used to coat the walls of such trucks or trailers for this purpose. Recently, however, the use of petroleum oils or other non-biodegradable materials has been criticized and even prohibited due to environmental concerns. Ballenger, Jr. et al. propose a biodegradable release agent for use in hot-mix asphalt applications which comprises preparing an aqueous dispersion of a vegetable oil which is emulsified in water using suitable emulsifiers, such as a sorbitol based emulsifier.
Leahy (U.S. Pat. No. 5,194,584) also disclose and teach the necessity for producing a non-toxic and biodegradable release agent that can be used in industrial applications. Leahy discloses a concrete release agent which comprises a small amount of tall oil uniformly dispersed in a vegetable oil as a superior concrete form release coating composition.
In industrial applications, such as described above, it is recognized that the extremely large surface areas which must be coated, along with the frequency of coating, requires that the release agent composition be inexpensive. Further, the surfaces which are coated are many times vertical, and therefore, the release agent must sufficiently coat and adhere to such vertical surfaces to function properly. Finally, as stated above, the release agent should be non-toxic and biodegradable.
Several lecithin based release agents have been disclosed for non-industrial applications. In particular, several lecithin based release agents have been disclosed as cooking surface release agents. However, it is believed that each of these compositions fail to meet one or all of the above criteria for industrial application. Some examples of lecithin based cooking release agents, include the following disclosures: 1) Sejbal (U.S. Pat. No. 4,142,003): a low viscosity lecithin vegetable oil release agent incorporating 1 to 15% of a 190 or 200 proof ethanol. 2) Szuhaj and Yaste (U.S. Pat. No. 4,108,678): a release agent consisting of lecithin, alcohol and a mixture of a triglycol esters. 3) Szuhaj and Yaste (U.S. Pat. No. 4,127,419): a release agent consisting of lecithin, triglycol esters, alcohol and water. 4) Follmer (U.S. Pat. No. 3,896,975): a lecithin emulsion applied from a pressurized system as a cooking lubricant. 5) Carey (U.S. Pat. No. 3,821,007): a lecithin containing aerosol release material comprising vegetable shortening, vegetable oil, lecithin and wheat and soybean flour. 6) Rubin et al. (U.S. Pat. No. 3,661,605): an aerosol release agent composed of a homogenized dispersion of lecithin and water.
It is readily apparent from the compositions disclosed above, that such compositions are not adequate for industrial applications, wherein large surface areas must be coated. Aerosol sprays are certainly not practical for such large volume applications. Further, the ethanol containing compositions raise flammability concerns and applicator exposure issues.
Accordingly, the need exists for a release agent composition for industrial application which is biodegradable and non-toxic. Further, the preferred agent for industrial application must be inexpensive for application to large surface areas, such as truck boxes and other industrial equipment in such industries as the asphalt industry or concrete industry. The composition must be suitable for application to vertical surfaces to provide a non-stick surface thereto upon contact by the material in the container or other equipment.
The present invention addresses these needs, as well as other problems associated with release agents for industrial applications. The present invention also offers further advantages over the prior art and solves other problems associated therewith.